The outside layer of something that is baked is called the crust. Some people don’t like the crust because it’s hard, but for others, it’s their favorite part of the food:

  • French bread has a hard crust.
  • The pie crust of an apple pie is filled with apples.
  • Without the crust of a pizza, all you have is mozzarella and tomato sauce.

The topmost layer of a rocky planet is called the crust. The crust of the Earth is over four billion years old. The moon also has a crust.

earth and moon

Some things become hard on the surface with the passage of time. These things are said to be "crusty."

  • Snow often forms a crusty surface on the top.
  • The cook top of a stove gets full of crusty bits of food if it isn’t cleaned regularly.
  • Some people develop crusty deposits overnight around their eyelids and eyelashes.

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Published on December 26, 2012.